Do you notice that you don't really sound the same sometimes?

I've heard some people claim that they sound different every time they speak, sing and that they can choose to sound like anything... that they don't know what their actual voice is.

Sure we can do voice impressions but do you believe that a guy who's been singing with a "dark" manly sound (Sinatra) can actually change his voice to sound feminine like Chris Colfer just by changing how his tongue is (compressed or not) and gain like a full octave they never sung with before??

I've heard that you can sound like anyone with adjustments and twang (whatever that means)... (I dont fully believe this btw)